1. Field of the Invention
This invention relates to extrusion of shapes of metal, for example, and cooling such shapes as they are being extruded and subsequent to extrusion.
2. State of the Prior Art
Presently, aluminum extrusions are made by expressing profiles or shapes of aluminum through a die and cutting the shapes to length. More recently, use has been made of extrusion pullers for pulling the extruded shapes as the shapes are expressed from the extrusion press or die. Subsequent to extrusion, the shapes are moved to a cooling area so that additional shapes can be extruded. The cooled shapes are then stretched to straighten the shapes and are then cut to length. In order to hasten the cycle time, the shapes are typically cooled with air as they are extruded from the die. Further, as the shapes are passed through a cooling area and to the stretcher, additional air is blown onto the shapes, usually from below the shapes with large fans. These fans are typically very noisy and consume significant amounts of electricity. The air blown onto the shapes along the extrusion path is directed downwardly from a large manifold. It is known to provide a large deflector at a 45.degree. angle to the horizontal adjacent the bottom of the slat support table in an effort to direct at least a portion of the downwardly directed air upwardly against the profiles in the cooling area. Because of the limited amount of direction of the air to the deflector and because of escape of air beneath the other side of the slat conveyor, this deflector has been of marginal value.
The extruded profiles are drawn along a series of slats which include heat-resistant bars, typically of carbon. After extrusion, the bars are immediately moved onto heat-resistant belts and are indexed through sets of belts into and through the cooling area. These belts are quite expensive and are frequently damaged by the heat of the aluminum extrusions. It is therefore desireable to slow down the cycle time to accommodate the cooling of the profiles so that the belts are not damaged by the extruded proviles.
Very complex shapes are frequently extruded in aluminum. These shapes include areas which are thicker than other areas. This differential thickness in cross-section results in differential cooling rates of the extruded profiles. Frequently, these complex shapes warp during cooling due to differential cooling of the shapes. Stretching of the profiles is not always effective to remove all of the warpage.